Sacroiliac Joint Injections

Alexis D. Kelekis and Dimitris Filippiadis

Clinical Relevance

At least once during their lifetime, the vast majority of the healthy population (70%-90%) will experience an episode of low back pain.¹ Degeneration or inflammation of the sacroiliac (SI) joint is a common cause (10%-27%).^2–5 However, defining the SI joint as the pain source can be quite difficult, mostly owing to overlapping of symptoms with those of facet or hip joint degeneration.^6,7 Therefore, infiltration as a diagnostic test can provide the foundation for establishing the SI joint as the pain source in these patients.

Symptoms of SI joint degeneration or inflammation can be persistent and refractory to conservative therapy (oral nonsteroidal antiinflammatory drugs [NSAIDs] and analgesics, bed rest, physiotherapy).2–5 Steroid administration is believed to achieve a neural blockade that alters or interrupts the neural processes of encoding and processing noxious stimuli, the afferent fibers’ reflex mechanisms, the neurons’ self-sustaining activity, and central neuronal activity patterns.⁸ In addition, corticosteroids inhibit synthesis and/or release of proinflammatory mediators, thus reducing inflammation. Local anesthetic interrupts the pain/spasm cycle and transmission of noxious stimuli.⁸

Indications 9–13

• Patient with unilateral or bilateral low back or groin pain without neuralgia

• Patient with sitting intolerance

• Patient with low back or groin numbness or buttock tingling

• Symptomatic patient (any of the aforementioned symptoms) with positive imaging findings for SI joint degeneration

Contraindications

Absolute 9–13

• Local sepsis/skin infection at the puncture site

• Bacteremia or any active systemic infection (including tuberculosis)

• Allergy to any component of the injected mixture (local anesthetic, corticosteroid)

• Patient unwilling to consent to the procedure

• Pregnancy (due to teratogenic effects of ionizing radiation)

• Underlying clinical entity that contraindicates corticosteroid therapy (ulcer, severe hypertension, severe congestive heart failure with fluid retention, etc.)

Relative 9–13

• Hemorrhagic diathesis (should be corrected before procedure)

• Anticoagulant therapy (should be interrupted before procedure)

• Immunodeficiency syndrome

• Allergy to contrast medium (in such cases, gadolinium can be used)

• Patient has already received maximum allowed dose of steroids for a given period (3-4 infiltrations within 6-12 month period)

Equipment 9–13

• All necessary material for extensive local sterility (scrubs, sterile drapes and coverings, gloves, and gauzes)

• Nonionic contrast medium

• Spinal needle, 22 to 25 gauge, 90 or 110 mm length

• Syringe (n = 2), 3 to 5 mL (for contrast medium and injectate)

• Injectate containing local anesthetic (e.g., lidocaine hydrochloride or bupivacaine hydrochloride) and long-acting steroid (e.g., betamethasone, methylprednisolone, or cortivazol) at 1 : 1.5 ratio (total injectate volume ≈ 2.5 mL)

• For diagnostic purposes, a local intraarticular anesthetic alone is injected.

Technique

Anatomy and Approaches

The SI joint is a diarthrosis between the sacral and iliac bones. The joint itself consists of two parts: inferiorly there is a synovial cartilaginous joint, and posterosuperiorly there is a fibrous part.⁹ The sacral cartilage is 3 to 5 mm thick, and the iliac cartilage is only 1 mm thick.⁹ The ventral rami of L4 and L5, the superior gluteal nerve, and the dorsal rami of S1, S2, S3, and S4 nerves innervate the SI joint.^1,2,10 In addition, the joint capsule and ligaments contain nerve fibers.^2,3,9

SI joint infiltration is a minimally invasive image-guided technique that is performed on an outpatient basis. Fluoroscopy, computed tomography (CT), and magnetic resonance imaging (MRI) can be used for imaging guidance.9–13 Although ionizing radiation is absent in MRI, the required cost and time are considered significant disadvantages. CT exposes the patient to ionizing radiation but can be reserved for cases with significant joint degeneration where intraarticular needle positioning is difficult.^14–16 Fluoroscopy provides faster and dynamic needle placement with real-time evaluation of the contrast medium’s spread inside the joint, which will verify both the desired and the extravascular needle position.^17–20 Cone beam CT (with pulsed fluoroscopy) may provide guidance (with fluoroscopic images, axial, and multiplanar reconstruction [MPR] CT-like images) at low radiation levels for both the patient and the medical staff.

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